Problem: $\sum\limits_{t=0}^{1 }{{(4-t)}}=$
Answer: What is the question asking for? $\sum$ tells us to find the sum. The question is asking for the sum of the values of $4-t$ from $t = 0$ to $t = 1$. Evaluating $\begin{aligned} \sum\limits_{t=0}^{1 }{({4-t})}&= (4-0) + (4-1) \\\\ &= 4 + 3 \\\\ &= 7\end{aligned}$ The answer $\sum\limits_{t=0}^{1 }{({4-t})}=7$